US3413413A - Switching arrangement for the transmission of direct current telegraph signal units - Google Patents

Switching arrangement for the transmission of direct current telegraph signal units Download PDF

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Publication number
US3413413A
US3413413A US398454A US39845464A US3413413A US 3413413 A US3413413 A US 3413413A US 398454 A US398454 A US 398454A US 39845464 A US39845464 A US 39845464A US 3413413 A US3413413 A US 3413413A
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Prior art keywords
line
direct current
transmission
telegraphic
transmitting
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Expired - Lifetime
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US398454A
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English (en)
Inventor
Anton J Peisl
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Siemens AG
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Siemens AG
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
    • H04L25/03127—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals using only passive components
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/08—Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults

Definitions

  • ABSTRACT OF THE DISCLOSURE A circuit arrangement for the line transmission of direct current telegraph signal elements in which a transmitting device and a receiving device is connected by a symmetrical conductive line extending therebetween in which a low resistance mismatching is effected at each end of the line between such end and the adjacent associated device.
  • the invention relates to a circuit arrangement for the transmission of direct current telegraphic signal elements over lines symmetrically and conductively connected with sending and receiving devices.
  • each receiving direction has a certain response threshold, and therefore a lowering of the step amplitude in deformed telegraph signal elements leads to a contrary time displacement of the response and drop out time point in each signal element, whereby the actual signal element length of the respective telegraph signal elements delivered by the receiving device is altered with respective to the desired signal element length.
  • This is generally termed telegraphic distortion. Because of the cross-talk interference and for reasons of the distortions mentioned, direct current telegraphy at speeds of more than 200 baud heretofore has been fundamentally impossible.
  • tone frequency pulses were utilized, because amplifier circuits for tone frequency pulses are technically considerably simpler to build than those for direct current pulses.
  • a disadvan- States Patent 3,413,413 Patented Nov. 26, 1968 tage of this technique is that a considerably greater expenditure with respect to circuit technology is required, since the direct current pulses produced at the transmitting end in any such device have to be converted into tone frequency pulses and at the receiving end reconverted into direct current pulses.
  • the invention has as its problem the creation of a circuit arrangement for the transmission of direct current telegraphic signal elements over symmetrical and conductively connected lines with transmitting and receiving devices inserted therein, which permits extremely wide latitude in the choice of the telegraphic transmission speed.
  • the invention proceeds with the concept of utilizing a low telegraphic transmitting voltage for the reduction of cross-talk interference, but to exclude to a high degree the telegraphic distortion simultaneously associated therewith, which heretofore made the transmission fundamentally impossible at higher signal element speeds and along longer lines, by a low resistance mismatching of the transmitting and receiving devices.
  • this problem is solved by an arrangement in which each transmitting device and each receiving device is connected to the appropriate line by a low resistance mismtach.
  • a distortion reduction by an arrangement in which, within the receiving device, there is inserted a line distortion corrector which consists of an RC-member in each conductor, operative to attenuate the amplitude of the longer current steps with respect to the amplitude of the shorter current steps.
  • FIG. 1 illustrates a schematic wiring diagram of a transmission path arranged according to the invention
  • FIG. 2 illustrates the circuit diagram of a low ohmic mismatching member
  • FIG. 3 illustrates a schematic wiring diagram of a direct current amplifier utilized in accordance with the invention
  • FIG. 4 illustrates a schematic wiring diagram of a low pass filter utilized in accordance with the invention.
  • FIG. 5 illustrates a schematic wiring diagram of a line distortion corrector utilized according to the invention.
  • the internal resistance of the entire transmitting device with respect to the line is made so low, for example 400, that it lies considerably below the impedance of the line T11, whose value amounts, for example, to 6009.
  • the transmitting voltage is so established that over the coupling capacitance C at the terminals resistance R1 of T12, on transmission of a test text there occurs maximally 0.35 mv. psophometrically measured noise voltage.
  • the transmitting voltage amounts to about 400 mv., at 6009 and the telegraphic current to about 0.2 ma with a line length of about 20 km.
  • the transmission, with ground symmetrical line termination is substantially unaffected by external interference.
  • the resistance mismatching of the line to the transmitting device can also be achieved through a correspondingly low internal resistance of solely the sending device.
  • a low internal resistance of the electronic sending relay ETSl at the low telegraphic transmitting voltage necessary for response of cross-talk is attainable simultaneously with sufiicient freedom in transmission distortion, only with greater expenditure.
  • the relatively low receiving level at the output of line T11 for example, 30 mv., is amplified about 20 times by the direct current amplifier GV, so that the electronic receiving relay ETSZ connected to the amplifier output is controlled with certainty.
  • the incoming telegraphic signal elements are thereby transmitted to the receiving subscriber T112.
  • the transmitting device is matched to the line only through the longitudinal resistance which raises the line time constant.
  • FIG. 2 illustrates an example of low resistance mismatching member utilized in the practice of the invention, which is composed of the ohmic resistors R3, R4 and R5.
  • the desired operating voltage can be set by the adjustable resistor R3.
  • the resistor R3 determinatively influences the time constant of the line path.
  • the resistor R3 is set at about 409.
  • FIG. 3 there is illustrated a symmetrical direct current amplifier GV utilized according to the invention, which in this example is a push-pull amplifier. It consists primarily of the two transistors Trl and TrZ operated in class A amplifier operation, in which the two transistors are selected for symmetry with respect to their characteristic curves. Both transistors receive the base bias voltage over corresponding resistors R6 and R7 or R9, inserted between the respective bases and collectors, the neutral setting of the push-pull amplifier being effected by adjustment of the variable resistor R6. The bases of the two resistors are directly connected with the line end.
  • resistor R8 which determines the input resistance of the direct current push-pull amplifier, which resistance, for example, amounts to 3009. This resistance thus also is considerably lower than the line impedance of, for example,
  • the mismatching member to be provided on the receiving end which is designated as FAG2 in FIG. 1 is included in the amplifier circuit.
  • the output side there are inserted in such direct current push-pull amplifier inductances L1 and L2, which, together with the input capacitance of the electronic receiving relay ETSZ, connected at such output side in FIG. 1, form a low pass filter for the removal of high frequency interference voltages.
  • FIG. 4 there is illustrated a low pass filter utilized according to the invention, which can be inserted in the transmission path shown in FIG. 1 between the electronic sending relay ETSl and the mismatching member FAGl, illustrated in FIG. 4 as constructed in accordance with FIG. 2 but including an additional shunt resistor.
  • This low pass filter represented in FIG. 4, according to the invention is so dimensioned that it sufficiently suppresses the second harmonic of the fundamental telegraphic frequency.
  • FIG. 5 is presented the schematic wiring diagram of a line distortion corrector composed of simple RC members R10, C1 and R11, C2 which, in the embodiment illustrated are disposed ahead of the amplifier GV.
  • a line distortion corrector composed of simple RC members R10, C1 and R11, C2 which, in the embodiment illustrated are disposed ahead of the amplifier GV.
  • R10, C1 and R11, C2 which, in the embodiment illustrated are disposed ahead of the amplifier GV.
  • an RC member which in each case attenuates the amplitude of the longer current steps with respect to the amplitude of the shorter current steps. If, within the scope of the invention, it is desired to dispense with the symmetry, one RC member in one conductor could be enlarged.
  • the present invention is not restricted to the transmission of telegraphic messages, as described in the disclosed example, but can be utilized in the same scope for any kind of message transmission in pulse form. Moreover, obviously within the scope of the invention there may be present, between the two subscribers and the line, selector switching means or branch-oft switching means for building up or branching off of a communication path.
  • FIG. 1 on the left hand side, there is represented a transmitting subscriber T 118 and on the right hand side a receiving subscriber Tn2.
  • the transmitting subscriber TnS is connected to a transmitting device, comprising the electronic relay ETSl and the current supply StV.
  • the transmitting device Through the capacitance C the sending device is adjusted to full ground symmetry.
  • a mismatching member FAGI In order to reduce the telegraphic voltage to the value allowable for reasons of cross-talk, and simultaneously to terminate the line with a low resistance according to the invention there is inserted between the transmitting device and the line T11 a mismatching member FAGI, which will be considered in greater detail in connection with FIG. 2.
  • a line T12 adjacent to this telegraphic line is also illustrated in this embodiment.
  • the coupling capacitance C present between the two lines T11 and T12 produces a cross-talk attenuation of 7.0 Np at 800 C. This value is to be regarded as the poorest crosstalk attenuation value which can be attained in non-defective local cables.
  • FAG2 low resistance mismatching member
  • the construction of such direct current amplifier will be considered in greater detail in connection with the description of FIG. 3.
  • This direct current amplifier together with the electronic receiving relay connected to the outlet side thereof, constitutes the receiving device of subscriber T112.
  • a circuit arrangement according to claim 3, wherein the low pass filter arranged at the transmitting .device is so dimensioned that it sufiiciently suppresses at least the second harmonic of the fundamental telegraphic frequency.
  • the direct-current amplifier is constructed as a push-pull amplifier comprising transistors operated in class A operation, with the bases of the transistors being directly connected to the line.
  • the direct-current push-pull amplifier is constructed as a push-pull amplifier comprising transistors operated in class A operation with the bases of the transistors being connected with the line over a line distortion connector.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US398454A 1963-09-23 1964-09-22 Switching arrangement for the transmission of direct current telegraph signal units Expired - Lifetime US3413413A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES0087452 1963-09-23

Publications (1)

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US3413413A true US3413413A (en) 1968-11-26

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US398454A Expired - Lifetime US3413413A (en) 1963-09-23 1964-09-22 Switching arrangement for the transmission of direct current telegraph signal units

Country Status (6)

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US (1) US3413413A (de)
BE (1) BE653460A (de)
DE (1) DE1251798B (de)
DK (1) DK122698B (de)
NL (1) NL154380C (de)
SE (1) SE312574B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932712A (en) * 1972-06-14 1976-01-13 Stromberg-Carlson Corporation Telephone transmission system
US4734919A (en) * 1981-02-20 1988-03-29 Gold Star Tele-Electric Co., Ltd. Incorporated Circuit for serial data communication and power transmission
WO2001061954A1 (en) * 2000-02-17 2001-08-23 Ic-Routing Limited Serial communication system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB261338A (en) * 1925-11-12 1927-03-17 Felten & Guilleaume Carlswerk Artificial line for use in cross-talk calibration in telephony
US2515058A (en) * 1945-06-01 1950-07-11 Roquet Raymond Jacques Charles Process and apparatus for reducing the distortion in the transmission of signals
US3090009A (en) * 1958-12-30 1963-05-14 Bell Telephone Labor Inc Noise figure improvement in radio receivers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB261338A (en) * 1925-11-12 1927-03-17 Felten & Guilleaume Carlswerk Artificial line for use in cross-talk calibration in telephony
US2515058A (en) * 1945-06-01 1950-07-11 Roquet Raymond Jacques Charles Process and apparatus for reducing the distortion in the transmission of signals
US3090009A (en) * 1958-12-30 1963-05-14 Bell Telephone Labor Inc Noise figure improvement in radio receivers

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932712A (en) * 1972-06-14 1976-01-13 Stromberg-Carlson Corporation Telephone transmission system
US4734919A (en) * 1981-02-20 1988-03-29 Gold Star Tele-Electric Co., Ltd. Incorporated Circuit for serial data communication and power transmission
WO2001061954A1 (en) * 2000-02-17 2001-08-23 Ic-Routing Limited Serial communication system

Also Published As

Publication number Publication date
DE1251798B (de)
SE312574B (de) 1969-07-21
NL6410498A (de) 1965-03-24
NL154380C (nl) 1982-01-18
NL154380B (nl) 1977-08-15
BE653460A (de)
DK122698B (da) 1972-03-27

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